results: All diarylheptanoids up-regulated estrogen-responsive genes in estrogen-responsive breast
cancer cells (MCF-7). In HepG2 cells transfected with estrogen receptor (ER) β or diffrent ERα
functional receptor mutants and the Vit-ERE-TATA-Luc reporter gene, all diarylheptanoids induced
transcription through a ligand-dependent human ERα-ERE–driven pathway, which was abolished
with ICI 182,780 (ER antagonist), whereas only D2 was active with ERβ. An ERα mutant lacking
the functional AF2 (activation function 2) region was not responsive to 17β-estradiol (E2) or to any
of the diarylheptanoids, whereas ERα lacking the AF1 domain exhibited wild-type–like activity. D3
markedly increased uterine weight and proliferation of the uterine epithelium in ovariectomized
mice, whereas D1 and D2 were inactive. D3, like E2, up-regulated lactoferrin (Ltf) gene expression.
Th responses to D3 in the uterus were inhibited by ICI 182,780. In addition, D3 stimulated both
classical (Aqp5) and nonclassical (Cdkn1a) ER-mediated gene regulation.